Laser spot projector

Abstract

Disclosed is a laser spot projector for use with a laser coagulation system in which a laser beam is radiated as a focussed spot into a portion selected to be thermally coagulated. A laser source produces a laser beam, and a focussing lens focusses the laser beam on the selected portion in the form of a focussed laser beam spot. A variator lens is displaceably arranged between the laser source and focussing lens for changing the magnification of the laser spot depending upon the displacement of the variator lens. The variator lens is selectably displaceable to two separate positions where the image point is conjugated with the object point with respect to the variator lens. This arrangement makes it possible to selectably provide two focussed laser beam spots each having a different spot diameter.

We claim: 
     
       1. An apparatus for ophthalmic laser treatment of the eye of a patient, comprising: slit image projecting means for producing a slit of light and projecting a slit image into the eye of a patient to illuminate the eye to enable a determination as to the treatment portion of the eye to be treated, the slit image projecting means including a source of light, and means for forming the light from the light source into a slit image composed of two slit image components; laser beam projecting means for projecting a laser beam into the eye of the patient for treating the eye; wherein both the slit image projecting means and the laser beam projecting means include a common reflecting means for selectively reflecting the slit image and the laser beam toward the eye, the common reflecting means having two side portions positioned to reflect and direct the respective slit image components toward the eye to illuminate the eye to thereby determine the treatment portion, and a central portion positioned to reflect and direct the laser beam toward the determined treatment portion to treat the eye; and wherein the laser beam projecting means includes a laser source for producing the laser beam, a focussing lens for focussing the laser beam on the determined treatment portion of the eye in the form of a focussed laser spot, and a variator lens displaceably arranged between the laser source and focussing lens for changing the magnification of the focussed laser spot according to the position of the variator lens, the variator lens being displaceable to a first position such that its object point corresponds to one conjugate point of the variator lens and its image point corresponds to the other conjugate point thereof with the object and image points spaced apart a given axial distance from one another so that the focussing lens forms a first focussed laser spot on the determined treatment portion, and being displaceable to a second position such that its object point corresponds to the other conjugate point and its image point corresponds to said one conjugate point while maintaining the given axial distance between the object and image points so that the focussing lens forms on the determined treatment portion a second focussed laser spot having a spot diameter different from that of the first focussed laser spot. 
     
     
       2. An apparatus according to claim 1; wherein the laser beam projecting means includes means for holding the focussing lens at a fixed distance with respect to the determined treatment portion of the eye. 
     
     
       3. An apparatus according to claim 1; wherein the slit image projecting means includes a condenser lens for condensing the light from the source of light, and a deflection prism arranged between the condenser lens and the means for forming the slit image and having a roof-shaped surface, one half of which serves to deflect the condensed light toward one side portion of the common reflecting means through the means for forming the slit image, and the other half of which serves to deflect the condensed light toward the other side portion of the common reflecting means through the means for forming the slit image. 
     
     
       4. A laser spot projector for use with a laser coagulation system in which a laser beam is radiated as a spot onto a selected portion of an area to be thermally coagulated, the laser spot projector comprising: a laser source for producing a laser beam;   a focussing lens for focussing said laser beam on a selected portion of an area in the form of a laser spot; and   a variator lens displaceably arranged between said laser source and focussing lens for changing the magnification of said laser spot according to the position of the variator lens, said variator lens being displaceable to a first position such that its object point corresponds to one conjungate point of said variator lens and its image point corresponds to the other conjugate point thereof with the object and image points spaced apart a given axial distance from one another so that the focussing lens forms a first focussed laser spot on said selected portion, and being displaceable to a second position such that its object point corresponds to the other conjugate point and its image point corresponds to said one conjugate point while maintaining the given axial distance between the object and image points so that the focussing lens forms a second focussed laser spot having a spot diameter different from that of said first focussed laser spot.   
     
     
       5. A laser spot projector according to claim 4 including means for holding said focussing lens at a fixed distance with respect to the position of said selected portion. 
     
     
       6. An apparatus for directing a laser beam along an optical axis to a treatment point for use during a surgical operation, comprising: emitting means having means defining an aperture disposed at a definite object point on an optical axis for emitting a laser beam from the aperture along the optical axis; image forming means selectively displaceable along the optical axis to one of two selected positions for selectively forming two aperture images different in size according to the selected position of the image forming means at a common image point conjugated with the object point with respect to the image forming means to thereby maintain the axial distances between the aperture and one of the two aperture images and between the aperture and the other of the two aperture images equal to each other; and focussing means disposed between the common image point and the treatment point on the optical axis for focussing the aperture image selectively formed at the common image point onto the treatment point to form thereon a corresponding focussed aperture image so that the laser beam travelling along the optical axis is irradiated onto the treatment point in the form of a focussed spot which corresponds to the focussed aperture image and which has a size determined according to the selected position of the image forming means. 
     
     
       7. An apparatus according to claim 6 wherein the emitting means includes an optical fiber for transmitting therethrough the laser beam, the optical fiber having a top edge defining an aperture for emitting therefrom the transmitted laser beam. 
     
     
       8. An apparatus according to claim 6 wherein the image forming means comprises a variator lens operative when placed in one of the two selected positions to form an enlarged aperture image and operative when placed in the other selected position to form a reduced aperture image. 
     
     
       9. An apparatus according to claim 8 wherein the focussing means comprises an objective lens for magnifying the enlarged and reduced aperture images with the same rate. 
     
     
       10. An apparatus according to claim 9 wherein the objective lens is positioned a fixed distance from the treatment point.